When a file is copied up in overlay, we have already created file on upper/
with right label and there is no need to copy up selinux label/xattr from
lower file to upper file. In fact in case of context mount, we don't want
to copy up label as newly created file got its label from context= option.
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
security/selinux/hooks.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index c82ee54..4fda548 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3290,6 +3290,21 @@ static int selinux_inode_copy_up(struct dentry *src, struct cred **new)
return 0;
}
+static int selinux_inode_copy_up_xattr(const char *name)
+{
+ /* The copy_up hook above sets the initial context on an inode, but we
+ * don't then want to overwrite it by blindly copying all the lower
+ * xattrs up. Instead, we have to filter out SELinux-related xattrs.
+ */
+ if (strcmp(name, XATTR_NAME_SELINUX) == 0)
+ return 1; /* Discard */
+ /*
+ * Any other attribute apart from SELINUX is not claimed, supported
+ * by selinux.
+ */
+ return -EOPNOTSUPP;
+}
+
/* file security operations */
static int selinux_revalidate_file_permission(struct file *file, int mask)
@@ -6077,6 +6092,7 @@ static struct security_hook_list selinux_hooks[] = {
LSM_HOOK_INIT(inode_listsecurity, selinux_inode_listsecurity),
LSM_HOOK_INIT(inode_getsecid, selinux_inode_getsecid),
LSM_HOOK_INIT(inode_copy_up, selinux_inode_copy_up),
+ LSM_HOOK_INIT(inode_copy_up_xattr, selinux_inode_copy_up_xattr),
LSM_HOOK_INIT(file_permission, selinux_file_permission),
LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
--
2.7.4
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